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Knowledge Discovery with NLP (Basic Search) – All Databases

How to use Ovid’s Basic Search (NLP) to search quickly and efficiently across different databases, either individually or in combination, using words, phrases or sentences.

Databases – All

Ovid Training Team

2024-10-27

79 visits

Background

When using biomedical databases for research, a common problem for beginners and advanced users alike, is how to find appropriate and relevant terms for the subjects being investigated. This could be because the user is unfamiliar with the subject or is working with the database from another language that differs from the language in which the subject terms are expressed. Or that the subject is new and that a consensus has not formed around key ideas and concepts and hence, have not yet found their way into the controlled vocabularies that are the basis of database thesauri, such as MeSH for Ovid MEDLINE and Emtree for Embase on Ovid.  

In such cases Ovid’s Basic Search can help. A natural language processing (NLP), relevancy ranking search engine, the Basic Search enables you to enter terms as simple expressions in any sequence. That is to say, there is no need to add Boolean operators or wildcard symbols or expressions. The entered terms are compared against those in a proprietary lexicon that Ovid has built to support the Basic Search and, following a statistical evaluation and ranking process, returns results on the basis of their calculated relevance to the terms you originally entered.

One of the many advantages of the Basic Search is that it executes on all the text fields of the database’s records. So, if the entry terms are found in the Subject Headings of the record or the Keywords, these will be highlighted. In this way you can see how the database is treating your original entry terms and subsequently make more precise searches using the database’s thesaurus or focused free term searching options. Being a field blind search, the Basic Search operates this way across all databases on Ovid.

Practice Suggestions

  1. Enter the following sentence, complete ‘as is’, into the Basic Search on Ovid MEDLINE:
    do omega-3 fatty acids prevent cardiovascular disease?
    How many terms in the sentence have been flagged as MeSH (Tree) terms?
  2. Limit the above search in point #1 firstly to Five Stars and then secondly, to publication years 2020 – Current. What ‘type’ of searches are these two latter ones: Basic or Advanced?
  3. Run the three line search from point #2 above in Embase on Ovid or in any another database your institution has subscribed to. Have you had to change the search in any way for it to run successfully?

Search Stategy

adolescents adhd ritalin adverse effects

limit 1 to five stars

limit 2 to yr="2020 - Current"

Launch Search

Reviewers

Primary: Michael Fanning

Secondary: Charlotte Viken

Review Date: 2024-10-27

Expiry Date: 2025-10-27

Original search produced by:

Ovid Training Team

References:

Ovid Online Help
Basic Search

OvidGO! / Skills Videos
Finding search terms
Highlighting on Ovid explained
Publication year limit

Citation:

OvidGO! Portal. Focused Searches: Knowledge Discovery with NLP (Basic Search) – All Databases [Internet]. London (UK): Ovid Training Team (Editors); 2024 [updated 25 October 2024; cited 30 October 2024]. Available from: https://tools.ovid.com/ovidgo/searches/view.php?id=51